Welcome to Bimmerfest -- The #1 Online Community for BMW related information! Please enjoy the discussion forums below and share your experiences with the 200,000 current, new and past BMW owners. The forums are broken out by car model and into other special interest sections such as BMW European Delivery and a special forum to voice your questions to the many BMW dealers on the site to assist our members!

Hi,
I was wondering if anyone could help us, we have just bought a X5 & the spare key battery was dead, so I found instructions to replace it, I also got the guide how to reprogram the spare key, which I carried out, the first way ( using a working key) did not work, so I used the second way, this only half worked, I could open the boot & unlock the doors, but would not lock, I tried it a couple of times & got the same result, so I gave up, I tried to start the car with the main key, but it would not start, it just made a electrical click, now i'm stuck with a nice X5 on my drive that don't work.
If anyone has had this problem & would share what they know it would be much appreciated.
Thanks
John

Ignoring remote issues for the moment, if the key won't start the engine then the transponder in the key is dead and you must buy a new key. The transponders in the keys just die after awhile (I've seen people complain after as little as 5 years) and it isn't a component that can be replaced with off-the-shelf components (like the rechargeable battery). The ignition and the key have to be paired so you will need to contact a BMW dealership to replace the key as BMW will have to manufacture it. This happened to me after I purchased my 2005 last year. I only had one key and it stopped starting the engine when placed in the ignition.

The dealership will need proof of ownership (vehicle registration receipt), proper identification (drivers license), and the VIN number of the X5. You will need to present these items in person and it can take several days for the key to be sent to the dealer (mine provided an overnight shipping option for an extra fee). Once you go in to pick up the new key they can program the remote (or you can do it yourself using the instructions you found).

These remote keys confound so many owners...here's some info that may help understand the key...although it may do nothing to help your problem.

The remote keys contains 3 features/systems that are all independent of each other but work in conjunction within the housing of the key and the 3 operating systems:

EWS - immboliizing "drive-a-way-protection" that uses a transponder (transmits & receives data) that shuts down fuel/spark/ignition until an ISN (individual serial number) that is shared by all the components of EWS verify that all the ISNs are the same. This feature is self-powering and communicates on a 125 KHz AM signal that is sent from the EWS control module to the Ring Antenna (around the ignition) which then sends the signal to the EWS EEPROM (transponder chip) which is soldered to the IC board inside the key (on the e53's remote key). The only way to communicate with the EWS system is through dedicated hardware/software (there's no driveway initializing short-cuts that communicate with EWS)

DWA - anti-theft alarm siren system ... transmits a 315 MHz or 433 MHz signal (one-way) to the receiver in the roof of the e53 which then sends a signal to the GM to arm/disarm the alarm siren and monitoring sensors (interior/tilt/hood/doors/fuel filler door) as well as activate the DWA LED (clown nose) beneath the rear view mirror. This feature is powered by the rechargeable battery that is inside the key. This feature can be initialized to other BMWs that use the same radio frequency and system (e46/e38/e39/Z3/e53/Z4).

FZV - keyless locking/unlocking of the central locking system ... also transmits a 315 MHz or 433 MHz signal (one-way) to the receiver in the roof of the e53 which then sends a signal to the GM and on to the central locking system to lock/unlock the doors/tailgate/fuel filler door. This feature is also powered by the rechargeable batterythat is inside the key. This feature can also be initialized to other BMWs that use the same radio frequency and system (e46/e38/e39/Z3/E53/Z4).

When you opened your spare and replaced the battery...how long did you allow the key's battery to recharge? The ability to UNLOCK the vehicle but not lock it...is one of the fail-safes of the keyless entry system that is an indicator of low battery voltage (in the key). It can take up to 30 hours to recharge a fully discharged key (see the 3rd bullet in the remote key info below:

To get your original key working again, you may need to take it to a dealer...or find someone that has the hardware/software that can communicate with the control modules. It sounds like you need to resync your key with the other EWS modules if it no longer starts the car. Again, the key does NOT require the battery inside the key to start the car...but it does need to be synced with the other EWS components to work properly (see the very last sentence in the info below).

Also note that the FZV signal is picked up by the antenna built into the rear window, which then passes that signal on to the receiver in the roof...where as the EWS signal is picked up by the ring antenna around the ignition...again, these are 2 separate systems that are working in conjunction with each other:

FYI: below is the instructions for reinitilizing the FZV/DWA (lock/unlock & arm/disarm) features of the remote keys. The instructions must be followed to the "T". Do NOT fudge, skip, combine, ignore any of the steps...and ALL remote keys must be programmed DURING the SAME session. Any remote key not initialized during the same session will no longer have the ability to lock/unlock & arm/disarm the car. It will start the vehicle but the FZV/DWA feature will no longer work:

I was wondering if anyone could help us, we have just bought a X5 & the spare key battery was dead, so I found instructions to replace it, I also got the guide how to reprogram the spare key, which I carried out, the first way ( using a working key) did not work, so I used the second way, this only half worked, I could open the boot & unlock the doors, but would not lock, I tried it a couple of times & got the same result, so I gave up, I tried to start the car with the main key, but it would not start, it just made a electrical click, now i'm stuck with a nice X5 on my drive that don't work.

I'm assuming you did not cut open the main key that now only makes an electrical click and does not start the car. This sounds like the car battery is dead. If you did cut open the key then you might have damaged the EWS portion of the key that enables starting of the car. The key programming does not have anything to do with being able to start the car or the battery in the key. Key programming is only for syncing up the keyless entry buttons to lock, unlock and pop the boot remotely. For the key that you say only half works where it can open the boot and unlock the doors. It sounds like you might have damaged a component or two on the circuit board when you cut it open. Check out these pictures of some genius key repair work bmwgm5.com/kf_wos.htm